The first print is the upper board arm for the B3500 Portable. The picture following the print shows the lower arms level with the ground. The board and goal are straight at this point. The spacing between the upper and lower arms is the same on the pole as it is on the backboard frame. The backboard frame, the pole, and the upper and lower arms for a rectangle at this point.

The next print is for the lower board arms for the B3500 Portable. The picture following the print shows the goal extended to maximum height. The rectangle described above moves as a parallelogram keeping the board and goal straight at all times.